A social media campaign aiming to save the threatened channel has garnered 200,000 follows as supporters warn of a loss of risk-taking programming catering for 16-34 year olds

The public backlash against the news that BBC3 is to close down as a broadcast channel continues to gather momentum, with 120,000 people now having lent their support to an online petition, while social media accounts aiming to save the TV station have followers totalling 200,000.

The online petition gathered over 85,000 signatures within 48 hours of going live. It has since added 35,000 more and looks set to reach its target of 150,000.

The petition asks BBC director general Tony Hall and the BBC Trust to reconsider plans to turn BBC3 into an online-only channel that would see shows hosted on BBC iPlayer.

Although Hall has promised that BBC3 output will also be aired in late evening slots on BBC1 and BBC2, the channel’s programme-making budget is still set to be slashed, with £30 million of a proposed £50 million saving providing a cash injection for BBC1 drama, while the remainder would be used to set up BBC3 in its new form.

Petitioners are concerned that BBC3’s function as a proving ground for new talent and groundbreaking programmes will be damaged and that its reduced budget and move online will leave its target demographic of 16-34-year-olds stranded.

“BBC Three has produced exciting, original television programming for 16-34 year olds since 2002,” said petition organiser Jono Read. “It has been a launchpad for programmes like Being Human, Torchwood, Russell Howard's Good News, Mighty Boosh, Bad Education, Gavin and Stacey, and Little Britain.

“Unlike other BBC channels it takes risks. It offers live debates and documentaries. It is also the channel for young people to go to for live music – something which is often relegated from the other main BBC television channels. Where else would dedicated coverage of Reading and Leeds, T In The Park, and Radio 1's Big Weekend fit if it was not on BBC Three?”

BBC3 won a Bafta for documentary Our War, about British troops on the frontline in Afghanistan, and saw shows like Gavin & Stacey and Torchwood make the leap to BBC2 and then BBC1, kick-starting the careers of stars like James Corden and Ruth Jones and Broadchurch writer Chris Chibnall.

Chibnall himself has been one of the campaign's vocal high-profile supporters, using Twitter to remind viewers of the many programmes the channel has been responsible for and describing the move to close it as "an own goal" and "a risky decision".

Uncle, Bad Education, Cuckoo, Revolution Will Be Televised, Him and Her, (RTS nom'd today) In The Flesh, The Fades, Being Human... #SaveBBC3